The emission at 669 nm of metal free phthalocyanine in toluene and 1-bromonaphthalene solutions

The emission spectrum of metal free phthalocyanine was recorded in toluene and 1-bromonaphthalene at different temperatures. The emission spectrum in toluene is characterized by a maximum at 698 nm and shoulders at 669, 738 and 782 nm at room temperature. At higher temperatures, the intensity of the shoulder at 669 nm increases relative to the intensity at the emission maximum, For a solution of metal free phthalocyanine in 1-bromonaphthalene at - 3 degrees C, excitation at 633 nm, which correlates with the 0-1 transition of the Q(y)-band, leads to emission at 705 nm characterized by a positive anisotropy. Excitation at 655 nm, which is attributed to the 0-0 transition of the Q(x)-band, leads to an emission with negative anisotropy. The shoulder in the emission spectrum at 669 nm is therefore attributed to the emission from the energetically higher Q(x)-state.